Nomogram for predicting left atrial appendage dense spontaneous echo contrast and/or thrombosis (dense spontaneous echo contrast/left atrial appendage thrombus): a comparison with CHADS2 and CHA2DS2-VASc scores based on three-dimensional transesophageal echocardiography.

BACKGROUND: Non-valvular atrial fibrillation (NVAF) carries a high risk of left atrial appendage thrombus (LAAT) and dense spontaneous echo contrast (dense SEC), the primary triggers of cardioembolic stroke. Conventional CHADS2 [congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, prior stroke/transient ischemic attack (TIA) score] and CHA2DS2‑VASc (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, prior stroke/TIA, vascular disease, age 65-74 years, Sex category score) scores lack left atrial appendage (LAA) morphological features, yielding limited predictive accuracy for dense SEC/LAAT. This study constructed a nomogram based on quantitative LAA parameters derived from three-dimensional transesophageal echocardiography (3D-TEE) to predict dense SEC/LAAT in NVAF patients and compared its performance with the two conventional clinical risk scores. METHODS: We retrospectively enrolled 159 NVAF patients who underwent 3D-TEE from July 2024 to December 2025, stratified into a dense SEC/LAAT positive group (n=50) and a negative group (n=109). Variables with severe multicollinearity [variance inflation factor (VIF) ≥10] were excluded. Univariate logistic regression (P<0.10) screened candidate predictors, followed by forward stepwise multivariate logistic regression to identify independent risk factors and construct a nomogram. Model discrimination, calibration and clinical utility were assessed via receiver operating characteristic (ROC) curves, calibration curves, 10-fold cross-validation, decision curve analysis (DCA) and clinical impact curves; inter-model area under the curve (AUC) comparisons used P<0.05 as the statistical significance threshold. RESULTS: Four independent predictors of dense SEC/LAAT were identified: D-dimer >0.550 mg/L [odds ratio (OR) =7.805, 95% confidence interval (CI): 2.044-29.795, P=0.002]; European Heart Rhythm Association (EHRA) score ≥ IIb (OR =6.255, 95% CI: 1.458-26.833, P=0.013); LAA poor echogenicity (OR =23.037, 95% CI: 5.651-93.909, P<0.001); LAA orifice morphology (OR =0.537, 95% CI: 0.296-0.975, P=0.041). The nomogram achieved an original AUC of 0.892 (95% CI: 0.839-0.945) at an optimal cutoff value of 0.29, with sensitivity 0.82, specificity 0.83, accuracy 0.82, and negative predictive value 0.91. It significantly outperformed CHADS2 (AUC =0.629) and CHA2DS2-VASc (AUC =0.606) (all P<0.05). Ten-fold cross-validation yielded an optimism-corrected AUC of 0.868 and a mean Brier score of 0.127; however, marked overfitting was observed (calibration slope =4.175, mean maximum calibration error =0.385). DCA confirmed sustained positive net clinical benefit within the 10-50% threshold probability range. CONCLUSIONS: The 3D-TEE-based nomogram shows acceptable discrimination for dense SEC/LAAT in NVAF patients and addresses the limitations of traditional risk scoring systems. Nevertheless, prominent overfitting prevents its direct clinical use without external validation and recalibration; it can serve as an auxiliary research tool for LAAT risk stratification.